“Estuarine ecosystem responses to single typhoon events have been well studied, but the impacts of successive typhoons on three-dimensional chlorophyll a—referring to how the pigment appears throughout a vertical water column and not just at the surface—remain understudied, despite successive typhoons being able to drive cumulative hydrological and ecological changes,” said first author Shaojing Guo, a doctoral candidate in the School of Marine Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory. … According to Guo, the study enhances understanding of how chlorophyll a responds to typhoons in and near the estuary under varying discharge conditions—a significant step toward forecasting variations in the estuarine ecosystem during typhoon events. “Under ongoing ocean warming and increasing extreme climate conditions, the frequency of successive typhoons and extreme droughts or floods may increase,” Guo said. “Through their cumulative impacts on physical and ecological processes, successive typhoons cause sustained strong disturbances to ecosystems in the estuary. Thus, our next step should pay more attention on the impacts of these events on the estuarine ecosystems in the future, which need to advance the simulating accuracy of our high-resolution physical-ecological model.” Fig. 2. Distribution of salinity (A to D) and temperature (E to H) observed at sections A and C in the summers of 2021 and 2022. The nearshore and shelf regions are delineated by dark and light gray patches, respectively. Fig. 3. Variations in salinity in Lingdingyang (left), the nearshore region (middle), and the shelf region (right) during successive typhoons in the CTL (A to C) and Ldis (E to F) runs. Vertical average changes for the CTL (red line) and Ldis runs (blue line) (G to I). The gray patches indicate the passage of Cempaka and Lupit. Fig. 9. Variations in surface currents before (A), during (B), and after (C and D) the passage of Cempaka, as well as before (E), during (F), and after (G and H) the passage of Lupit. (I to P) same as (A to H), but for the Ldis run. The blue line represents the 32-psu isohaline labeled as the river plume. 6 Fig. 13. Time series of mean Chla budget terms in Lingdingyang (A and B), the nearshore (C-F), and shelf (G-J) regions. Physical processes (Phy) are the sum of Hadv, Vadv, and Vdiff terms. Light red, green, and blue patches indicate the periods during typhoons, 1 to 3 d, and 4 to 10 d after typhoons, respectively. Fig. 14. Schematic diagram of Chla changes and primary mechanisms during Cempaka and Lupit. The light-yellow shading indicates the change in river plume, and the black lines are the boundaries between the Lingdingyang, nearshore, and shelf regions. The length of vectors indicates the intensity of runoff, current, and upwelling. The Chla and NPP density indicate their magnitude changes, and the gray patches represent the thickness changes of the BCM/SCM layer.